The present invention relates to an apparatus for determining the position of the focal point in a laser machining system in which a laser beam is transmitted via an optical fibre to a workpiece to be machined by the laser beam.
In laser material processing systems the laser beam is focused on a small area (spot) so that the high energy intensity can be used to machine (vaporize) the workpiece material. Laser machining systems are frequently used for cutting, welding and marking operations in the manufacturing industry. Thanks to the recent development of optical fibre technique such laser machining stations are designed with flexible transmission of the laser beam to the workpiece by means of optical fibres. In many cases a machining head is mounted in the arm of an articulated robot for manipulating the laser beam relative to the workpiece.
In a system in which the laser beam is fixed and the workpiece is moved, it is usually no problem to determine the position of the focus point of the laser beam. However, in case of a 7-axes robot manipulating the beam the determination is more difficult. For instance by collisions, exchange of optical components or robot maintenance the focal point might be displaced and the position has to be adjusted. Such adjustments, however, are usually trouble-some and time-consuming
The z coordinate position of the focal point is often displaced in high power machining systems if the optical system is not the best. Such displacement has usually not been considered in prior adjustment systems, due to the fact that the adjustments in such cases must be carried out at full laser power conditions.
It is an object of this invention to provide an improved apparatus for determining the position of the focal point in z as well as in the x and y coordinates.
It is a further object of this invention to provide an apparatus for determining the position of the focal point in the z coordinate also at full laser power condition.